The important data backup concept of ASUS UX21E series is off-site backup. The safest backup is to place data on different storage media and place the storage media in different buildings. This is the concept of off-site backup that is very popular recently, and the same can be applied to individuals. In addition to ASUS's considerate design of two disks in one machine and multiple disks in one machine, regular backup habits are the best way to preserve data.